Method for reducing an amount of ink used in printing an image

Abstract

A method for reducing an amount of ink used in printing an image includes processing data representing the image to distinguish each halftone region from each solid region, wherein each solid region is formed by boundary ON pixels connected to interconnected interior ON pixels and having a sum of a quantity of the boundary ON pixels and a quantity of the interior ON pixels satisfying a predetermined threshold quantity; performing halftoning on the interior ON pixels of each solid region to form a reduced number of interior ON pixels to achieve a desired gray scale level; and printing the image consistent with the halftone region(s), and consistent with the boundary ON pixels and the reduced number of interior ON pixels representing each solid region.

1 . A method for reducing an amount of ink used in printing an image, said image initially being represented by a plurality of ON pixels and a plurality of OFF pixels arranged as a plurality of regions including at least one halftone region and at least one solid region, said ON pixels representing dot locations where ink dots are intended to be placed on a print medium, comprising: 
 processing data representing said image to distinguish each of said at least one halftone region from each of said at least one solid region, wherein each solid region is formed by boundary ON pixels connected to interconnected interior ON pixels and having a sum of a quantity of said boundary ON pixels and a quantity of said interior ON pixels satisfying a predetermined threshold quantity;    performing halftoning on said interior ON pixels of each solid region to form a reduced number of interior ON pixels to achieve a desired gray scale level; and    printing said image consistent with said at least one halftone region, and consistent with said boundary ON pixels and said reduced number of interior ON pixels representing each solid region.    
   
   
       2 . The method of  claim 1 , wherein said desired gray scale level is selected from a plurality of possible gray scale levels.  
   
   
       3 . The method of  claim 1 , wherein said threshold is determined experimentally for a given halftoning scheme.  
   
   
       4 . The method of  claim 1 , wherein the act of printing is performed without modifying said at least one halftone region and without modifying said boundary ON pixels of said at least one solid region.  
   
   
       5 . The method of  claim 1 , wherein a minimum value of an average gray level corresponding to said desired gray scale level is determined by experiment.  
   
   
       6 . The method of  claim 5 , wherein said average gray level is varied to replace said at least one solid region with different shades of gray in a printed document representing said image.  
   
   
       7 . The method of  claim 1 , wherein each solid region has said sum that satisfies said predetermined threshold quantity, and there is no small isolated groups of OFF pixels.  
   
   
       8 . A method for reducing an amount of ink used in printing an image formed by a plurality of ON pixels and a plurality of OFF pixels arranged as a plurality of halftone regions and a plurality of solid regions, comprising: 
 processing data representing said image to distinguish said plurality of halftone regions from said plurality of solid regions, wherein each solid region is formed by boundary ON pixels connected to interconnected interior ON pixels and having a sum of a quantity of said boundary ON pixels and a quantity of said interior ON pixels satisfying a predetermined threshold quantity;    performing halftoning on said interior ON pixels of each of said plurality of solid regions to form a reduced number of interior ON pixels to achieve a desired gray scale level; and    printing said image consistent with said plurality of halftone regions and consistent with said boundary ON pixels and said reduced number of interior ON pixels representing said plurality of solid regions.    
   
   
       9 . The method of  claim 8 , wherein said desired gray scale level is selected from a plurality of possible gray scale levels.  
   
   
       10 . The method of  claim 8 , wherein said threshold is determined experimentally for a given halftoning scheme.  
   
   
       11 . The method of  claim 8 , wherein the act of printing is performed without modifying said plurality of halftone regions and without modifying said boundary ON pixels of said plurality of solid regions.  
   
   
       12 . The method of  claim 8 , wherein a minimum value of an average gray level corresponding to said desired gray scale level is determined by experiment.  
   
   
       13 . The method of  claim 12 , wherein said average gray level is varied to replace at least some of solid regions of said plurality of solid regions with different shades of gray in a printed document representing said image.  
   
   
       14 . The method of  claim 8 , wherein each solid region has said sum that satisfies said predetermined threshold quantity, and there is no small isolated groups of OFF pixels.